Norfolk Island Pine Diseases
Gary W. Moorman, Professor of Plant Pathology
| Disease | Symptoms | Pathogen/Cause | Management |
|---|---|---|---|
| ANTHRACNOSE | Small dead areas form on needles and the entire needle dies. Small black fungal fruiting bodies are seen in the dead tissue. Large portions of branches brown and needles fall. | Colletotrichum derridis | Avoid overhead watering. Keeping the surface of the foliage dry will prevent this disease. |
| BRANCH DROOP | Excessive drooping of branches although trunk is straight. Plants develop poorly. | Low light intensity | Provide at least 6000 ft-c of light to plants more than 6 inches tall. |
| ROOT ROT | Plants grow slowly and wilt. Roots are small, brown to black, and are soft and rotting. | Cylindrocladium or Pythium | Pot in pasteurize mix. Maintain even soil moisture. Etridiazole soil drench will protect against Pythium. |
| YELLOWING | Branch tips and the main growing tip is yellow instead of dark green. | Micronutrient deficiency | Apply a micronutrient solution. |
Active Ingredients and Trade Names of the Chemicals
| FRAC Group No. | Risk Level | Class | Active ingredient | REI Restricted Entry Interval | Trade names (EPA Reg. no.) |
|---|---|---|---|---|---|
| 14 | 1 | Thiadiazole | etridiazole | 12 | Truban (58185-7), Terrazole (400-416) |
Fungicides and Fungicide Resistance Management - Certain fungicides, usually systemic fungicides, are said to be 'at risk' to the development of resistance if they are used repeatedly. See the Risk Level in the above table (1 = low risk; 3 = high risk). The Fungicide Resistance Action Committee has developed a numbering system in which chemicals with the same FRAC Group number have the same mode of action (See http://www.frac.info/frac/index.htm ). It is recommended that chemicals at high risk be used sparingly and in rotation or mixed with chemicals with different modes of actions (different FRAC number).
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